JP3013314B1 - Seawater or freshwater purification method - Google Patents

Abstract

The present invention provides a method for purifying seawater or freshwater that can easily and efficiently remove and recover nitrogen, phosphorus, and the like remaining in a vast water area, and that can effectively use the recovered material as a resource. SOLUTION: A string 10 having a large number of dispersing threads is hung in seawater or fresh water, and a bivalve shell 12 having an adhesive thread is selectively spontaneously adhered to the dispersing thread in a large amount, so that floating suspended organic matter is taken up. Feed, grow and lift to land.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying seawater or freshwater using the adhesion properties of bivalves, and more particularly, to attaching tosole-adhering bivalves that inhabit the ocean to a dispersing thread, The present invention relates to a method for purifying seawater or freshwater that can purify seawater by growing it and, in some cases, recycle collected bivalves.

[0002]

2. Description of the Related Art In recent years, red tides and anoxic water masses have been frequently observed in the inner bays and coastal areas having metropolitan areas behind them due to eutrophication of water bodies. Such an eutrophication phenomenon not only deteriorates aquatic ecosystems, but also causes enormous damage to the fisheries industry and worsens the landscape.
It is a social issue as well as a water quality issue. The eutrophication phenomenon of seawater and freshwater refers to the nitrogen contained in water as domestic wastewater and industrial wastewater flow into the ocean and rivers, etc.
Phosphorus concentration increases, and this is the abnormal reproduction of phytoplankton that uses this as a nutrient source. Methods for suppressing this eutrophication phenomenon include: 1) physical methods by sand covering and dredging; 2)
There are known a chemical method of spraying lime and the like, and 3) a biological method of growing large plants such as water hyacinth.

[0003]

However, the physical method of 1) is costly and disrupts the marine ecosystem, the chemical method of 2) is not effective, and the biological method of 3) is not effective. Method has problems such as difficulty in treating the collected organisms,
None of them are widely used at the moment.
The present invention has been made in view of such circumstances, nitrogen and phosphorus remaining in a vast water area without imposing an environmental load,
It is another object of the present invention to provide a method for purifying seawater or freshwater that can easily and efficiently remove and recover living organisms without damaging the living organisms and that can effectively use the recovered material as a resource.

[0004]

According to the present invention, there is provided a method of purifying seawater or freshwater according to the present invention, wherein a string having a large number of dispersing threads is hung in seawater or freshwater, and a bivalve having an adhesive thread is formed. A large amount is selectively adhered to the dispersing yarn, and the suspended suspended organic matter is fed and grown to be collected on land. That is, phosphorus and nitrogen contained in seawater and freshwater serve as nutrients for phytoplankton, and they also feed on zooplankton. On the other hand, bivalves feed on these phytoplankton and their remains, and as a result nitrogen and phosphorus contained in seawater or freshwater are absorbed by the bivalves and nitrogen and phosphorus in seawater or freshwater are reduced. . Here, in the present invention, when hanging a string-like material provided with a large number of dispersed yarns, barnacles, sponges, shells and the like which require a certain area to adhere to the sea squirt are extremely difficult to adhere, As a result, a large amount of bivalves that adhere to the toe are attached, and the large amount of bivalves effectively removes suspended matter in water and purifies the water. Then, by pulling the string attached to the bivalves out of the water, a large amount of bivalves absorbing nitrogen and phosphorus can be easily collected. Then, the bivalves grown by the components of the suspended matter can be effectively used as feed, fertilizer, and the like. In addition, the bivalve with adhesive toes, that is, a bivalve having a function of taking out the body of the toes and fixing its own body to the adherend, for example, mussels, mussels, pearl oysters, mussels,
Black mussels, white mussels, zebra muscles, river mussels, etc. are applicable.

[0005] The dispersing yarn is a yarn having a thickness of, for example, 0.05 to 2 millimeters for easily entanglement of the clam of the bivalve, and is made of a biodegradable polymer material (biodegradable plastic) or the like. , Other natural or synthetic materials can be used. The biodegradable plastic refers to a plastic that can be decomposed by microorganisms in a natural environment, and includes, for example, aliphatic polyester, polysaccharide, polyamino acid, polyether, polyvinyl alcohol, and the like. Furthermore, Zo
ogloea bacteria and facultative autotrophic bacteria Alcalig
enes eutrophus is a poly-
It accumulates β-hydroxybutyric acid (PHB) as an energy storage substance, which is biodegradable and
It is a thermoplastic that melts at around 80 ° C,
Since they can be melt-molded into fibers and the like, these are also included in the biodegradable plastic according to the present invention. The above-mentioned dispersed yarn may be formed in an annular shape (loop shape) without a start end and an end so that the attached bivalve sole may not easily slip off. Thereby, falling off of the bivalves held by the string can be effectively prevented. Further, the string-like material may be made of a biodegradable plastic.

[0006] Bivalves grown by feeding with suspended organic matter that has ingested nitrogen or phosphorus are raised at an appropriate time,
The bivalves can be used as feed or fertilizer as it is or in some cases by processing such as tempura. In particular, when the string is made of biodegradable plastic, crushing treatment can be applied as it is without separating the string attached to the bivalve, so that the waste can be efficiently treated without generating extra waste. it can. The bivalve with an attached to thread may be a mussel. In this case,
In particular, by applying a mussel with excellent reproductive properties, taste, etc., it is possible to realize efficient purification of the water area and effective use of the collected mussel.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. FIG. 1 is a conceptual diagram illustrating a method for purifying seawater or freshwater according to an embodiment of the present invention.
Is a graph showing the relationship between the bivalve growth and the rope hanging period, FIG. 3 is an explanatory view of a string hanging in seawater, and FIGS. 4 (a) and (b) are descriptions of a feeding experiment and a control experiment, respectively. FIG. 5 and FIG. 5 are graphs showing the relationship between the cell density in the breeding water and the elapsed time, and FIGS. 6A and 6B are graphs showing the relationship between the elapsed time and the nitrogen concentration and the phosphorus concentration in the breeding water, respectively.

Referring to FIG. 1, an overall flow of a method for purifying seawater or freshwater according to an embodiment of the present invention will be described. As shown in FIG. 1, in a coastal sea area adjacent to an industrial area, factory wastewater and domestic wastewater containing nitrogen and phosphorus flow in through rivers and sewers throughout the year. For this reason, such water bodies contain a large amount of organic suspended matter originating from industrial wastewater or domestic wastewater, and flora and fauna plankton and the like, which use this as a nutrient source, are bred and red tide is easily generated. . When such an organic suspension precipitates on the seabed and accumulates as organic sludge, eutrophication progresses in a water area in the vicinity, such as appearance of an anoxic water mass. Therefore, in the present embodiment, first, a large number of cords 10 having dispersed yarns are prepared, and
One end of the zero is connected to the buoy 11 or the like, and is suspended and held in such a water area. Then, the mussel 12, which is an example of a bivalve with an attachment to the toe, is entangled with the dispersion thread and fixed to the cord 10. The mussels 12 can be cultured by feeding the suspended organic matter in water to the mussels 12. As a result, the suspended organic matter in the water is removed by the mussel 12, and the purification of the water can be performed over a wide range and efficiently. In addition, the grown mussels 12 can be pulled out of the water together with the string-like material 10 and collected on land, and used as it is or processed and used as food, or used as livestock feed or agricultural fertilizer.

Hereinafter, the significance of the present embodiment will be described more specifically. The ocean, which accounts for about 70% of the earth's surface area, is the ultimate destination for terrestrial materials and has been used as a reservoir with unlimited receptivity. The environment has deteriorated with the development of civilization by human beings, and it has become unable to fulfill its original function. The natural value of the ocean is under pressure from both physical and chemical aspects of human activity. Physical pressure refers specifically to landfills, artificial islands, port structures,
This refers to the disappearance of highly productive tidal flats and natural shores due to coastal structures and farms.Chemical pressure refers to red tides caused by the inflow of land-derived sediment, nutrients, and organic matter. Refers to the occurrence of oxygen-deficient water mass, rocky seashore, etc. One of the technologies for purifying such contaminated sea areas is to use the ecological characteristics of living organisms to attempt environmental remediation. There are few examples using living things. Originally, purification in nature is based on a food chain originating from spoilage decomposition by microorganisms. Since relatively large organisms such as mussels and mussels grow rapidly using organic suspended particles in phytoplankton and seawater as feed, these large organisms are consumed on land as food, feed, and fertilizer. It is thought that it can function as part of the food chain and promote water purification.

Therefore, in the present embodiment, an attempt was made to restore the environment using the ecological characteristics of the bivalve mussels such as mussels and mussels as the target water area of Dokai Bay in Kitakyushu City, Fukuoka Prefecture. The bay was once part of an inanimate zone along with the progress of water pollution, but after that, as a result of water purification measures such as sewerage development and factory drainage regulations, the water quality has been greatly improved.
It is a water area where many creatures including mussels and mussels are returning. But even today,
River water containing urban domestic wastewater flows into the narrow inner bay with a bay width of 1.2 km and a depth of 13 km, on the order of 190,000 to 300,000 m ³ / day, and contains a large amount of nutrients even though it is regulated. The current state is that the effluent from the factory drains, the bay is still overnutrition, and red tide and anoxic hydration are occurring. On the other hand, mussels are the most dominant species suitable for aquaculture in Dokai Bay, etc., and more efficiently return the marine environment to a healthy state by collecting food or fertilizer in a form that can be used by humans. Was thought.

(Field Water Quality Survey) First, the sea area near Tobata Wharf Pier in Dokai Bay was surveyed.
Water quality surveys were conducted for one year and five months from March to September 1997, and the transparency, water temperature, salinity, dissolved oxygen concentration, chlorophyll a concentration, etc. were measured at each water depth. Looking at the vertical distribution of water temperature, there was no difference due to water depth throughout the observation period. The highest water temperature was recorded in August 1996 and 1997. The water temperature in August 1996 was less than 28 ° C except for the extreme surface layer,
The water temperature in August 997 was above 28 ° C near the middle layer. The lowest water temperature was observed from January to February 1997, but never dropped below 10 ° C. Looking at the vertical distribution of salinity, 25.71 p in the surface layer in June 1996
su, a low salinity of 25.2 psu was observed on the surface layer in September 1997. In June 1996, salt stratification was observed, but in other months the salinity increases slightly as the water depth increases, but there is no significant difference between the surface and bottom layers. Was. Almost no change in dissolved oxygen concentration due to water depth was observed throughout the survey period.
Hypoxia in the summer was not confirmed. Looking at the vertical distribution of chlorophyll a concentration,
From July to August 1997, a significant increase in chlorophyll a concentration was observed. During the observation period, the highest chlorophyll-a concentration was found in the middle layer in August 1997.
It was 3 μg / liter. Thereafter, it rapidly decreased to 14 μg / liter in September. A similar tendency was observed in 1996. In the surface layer in August 1996, 51 μm was observed.
g / l but in September it was 12 μg / l. During the observation period, the lowest chlorophyll-a concentration was in the middle layer in December 1996, at 0.11 μg /
Liters.

(Survey of Dominantly Adhering Organisms) In such an environment, a survey was made of the predominantly adherent organisms for each depth. In this case, a single cable of 50 cm in length was connected to 12 Cremona S ropes made of a synthetic resin such as a blend of vinylon and polyester. 6 droops from the crater to the sea floor, and picked up every month. After measuring the total wet weight of the picked-up ropes, all the deposits were peeled off, the dominant species adhering per rope was identified, and the wet weight and the like were measured. As for the mussels, mussels and white squirrels, which were significantly dominant in the observed attached organisms, the total organic carbon content (TC) and the total organic nitrogen content (T
N) and the amount of total organic phosphorus (TP) were determined. TC,
For TN, a MT-3 type CHN coder manufactured by Yanagi Head Office was used, and for TP, colorimetric determination was performed by the molybdenum blue method.

As a result, the entire rope (No. 1 to 12)
Looking at the change over time in the wet weight of the deposit, it increased with each passing month, and reached a maximum value of 17 kg in October (dipping period: 6 months). In addition, the number of dominant species attached was 10 in October. Rope No. 1, 3, 5, 7, 9, 1
The species observed after dominant species identification was performed for a total of six strains, i. Mussels, mussels, and
There were scallops, oysters, magpies, barnacle barnacles, American barnacles, scorpionfish, hydroids, polychaetes, crustaceans and the like. In addition, the amount of CNP contained in the body tissues of the mussels, the mussels, the white squirrel, and the hydroids were measured. The CN ratio per dry weight of these dominant species is almost the same,
The highest ratio of P content to CN content was for hydro worms, and the lowest was for white squirrels. On the other hand, the highest amount of C and N per dry weight was the body of Kouroenkawa mussels, 437 mgC / g each.
(Dry weight) and 95.4 mgN / g (dry weight). The highest amount of P per dry weight was 21.0 mgP / g (dry weight) for hydroids. The amount of CNP contained in the body of Shiroboya was the lowest in all cases except for the shells of bivalves.

[0014] Based on these facts, a comparative study was attempted on species capable of recovering CNP most efficiently at actual sites. As a result, Shiroboya showed about 5 times the biomass of bivalves,
. It turns out that it becomes about 1.1 times when converted to N amount and about 0.5 times when converted to P amount.
Recovery of P was found to be more efficient. Considering the relatively low abundance and predominance of hydro worms only in the summer, it is difficult to use hydro worms systematically and artificially as an application to environmental restoration. it was thought. From the above, it was considered that when attempting to rehabilitate the environment using attached organisms in Dokai Bay, it is most efficient to use mussels and mussels.

(Bivalve Adhesion Experiment Investigation) The bivalve adhesion experiment investigation was conducted at Tobata Wharf Pier in Dokai Bay from April to October, 1995 and from April to September, 199.
The training was conducted three times from February to September 2007. Cremona S rope (50 cm) in 1995, and a green curing net made of Cremona in 1996 (50 cm long, 15 c wide)
m), a rope (50 cm) provided with a dispersion yarn made of vinylidene chloride in 1997 was used. As shown in FIG. 1, the attachment base was stuck to the upper layer (0-50 cm) and the lower layer (100-150 cm), and a buoy was attached to this. This apparatus was pulled out of seawater once a month, and one base was collected from each of the upper layer and the lower layer. The attached mussels and mussel were stripped off, and the numbers and shell lengths were measured. In addition, in the 1996 survey, new nets were attached to the upper and lower layers to clarify the amount of newly attached bivalve biomass every month, and then the equipment was immersed again in seawater. . The newly installed net was recovered the following month and the same work was performed.

As a result of examining the timing of the attachment of the mussels, individuals that adhered were confirmed from May to July. The numbers were highest in June for both upper and lower layers, with 300 and 144 individuals, respectively. The number of individuals that adhered in July was only two in the upper layer and the lower layer, and none of the individuals adhered by October thereafter. In addition, with regard to Kuroenkawa mussels, individuals that newly adhered were confirmed in July to October. The numbers were highest in August for both upper and lower layers, with 2236 individuals and 318
There were 0 individuals. Next, using the relational expression of mussel shell length and wet weight in Dokai Bay, biomass (wet weight) of mussel attached to rope and net
Was calculated. As a result, the largest biomass in the 1995 survey was July, with 0.2
The weight was 4 kg and the lower layer was 0.07 kg. Looking at the survey in 1996, the upper and lower classes reached a maximum of 2.06 kg / net and 1.04 kg / net in October, respectively. Looking at the 1997 survey, both upper and lower classes
7.81kg / rope, 4.69 each month
kg / rope. On the other hand, in the 1996 survey, Kouroenkawa mussels showed relatively large biomass. In addition, it is pointed out that the larva of mussel does not react to a chemical substance but rather its physical shape is decisive, and the larva prefers a fibrous substance. In addition, since fibrous substances were considered to be able to suppress the adhesion of competing species such as oysters and barnacles, which prefer a relatively hard adhesion base, a rope with vinylidene chloride dispersed yarn was used as the adhesion base in 1997. Using. By adjusting the structure of the attachment base and the charging time in this way, a remarkably large amount of biomass could be attached in 1997.

In addition to the bivalve adhesion experiment described above,
FIG. 2 shows the results of an example in which the material of the string used was changed. Here, Cremona S using a synthetic resin material such as a blend of vinylon and polyester is used.
Using a rope and a rope made of biodegradable plastic, the wet weight (g / m) per unit length of the biomass adhered and formed on each of the ropes, that is, the growth amount of bivalves was measured every month. As shown in FIG. 3, a rope 20 made of a biodegradable plastic, which is an example of a string-like material,
It has a large number of dispersion yarns 21 having a diameter of 0.01 to 1 mm and a length of 50 to 500 mm, and furthermore, each dispersion yarn 21 is formed in a ring shape as a whole and bundled in a rope body. ing. And a rope 20 hanging underwater
Has an upper end connected to the buoy 11 via an upper leash 22, and a lower end connected to a lower leash 23, and a weight (not shown) is fixed to the lower leash 23 as necessary. Thereby, it is comprised so that many ropes 20 may not be entangled mutually. As shown in FIG. 2, when the rope 20 made of a biodegradable plastic is used, it is possible to improve the selective adhesion to biomass, particularly to mussels, and to form the dispersed thread in a ring shape, so that the attached bivalve It can be seen that the amount of biomass can be significantly increased as compared with the case where the Cremona S rope is used by preventing the falling off of the biomass.

(Feeding Experiment) Subsequently, the following feeding experiment was carried out in a laboratory in order to evaluate the effect of environmental purification by such organisms as mussels. The feeding experiment was carried out for the mussels to estimate the feeding rate for each shell length and the assimilation rates for nitrogen and phosphorus (N, P). As shown in FIG. 4 (a), a purple mussel 33 is placed in each of the shell lengths S, M1, M2, L1, and L in an acrylic water tank 30 having a volume of 3 liters.
Two were introduced one by one. In addition, FIG.
Many points shown in (b) indicate phytoplankton used as bait. Next, natural seawater filtered with a filter having a pore size of 0.45 μm and a fixed amount of diatoms dominant in Dokai Bay in summer as prey were added to each tank as experimental breeding water. A water tank 30 containing a mussel 33 and a water tank 34 containing only prey organisms.
Was used as a control, and adjustment was performed using an air-rate device 35 so that the food particles in all of the water tanks 30 and 34 did not settle. Reference numerals 31 and 32 denote an Erlenmeyer flask and a funnel.

After the installation, the water temperature is 20 (° C.),
Under the condition of illuminance 370 (lux), mussels 33
POC in breeding water for 48 hours after opening
The rate of decrease in (particulate organic carbon) was measured, and the feeding rate for each shell length as shown in FIG. 5 was determined. Further, the amount of suspended particles reduced from 0 hours to 48 hours is defined as food consumption, and the TN of the entire water tank 30 from 0 hours to 48 hours is determined.
(Total nitrogen) and TP (total phosphorus) were determined to be assimilated by the mussel 33, and the assimilation rate was calculated. In addition, the POC concentration in the field is 50 to
POC in this range
Was used as the feeding rate. Here, the cell density in FIG. 5 indicates the density of phytoplankton, and FIG.
(A) and (b) show the corresponding nitrogen concentration and phosphorus concentration, and it can be seen that the respective concentrations decrease over time. When estimating the feeding rate from the reduction rate of suspended particles as in this experiment, the value differs depending on the particle density. Therefore, the average value of the feeding rate for the particle density observed in the field was used as the feeding rate for each shell length.
The assimilation rate of mussels was determined by directly measuring food intake and excretion. Assuming that everything consumed by respiration and metabolic energy is also assimilated,
The average assimilation rate of mussels is 39.6 for carbon (C)
%, Nitrogen (N) was 36.0%, and phosphorus (P) was 1%.

Hereinafter, a method of purifying seawater or freshwater using bivalves is considered based on the results of these experiments.
Under plankton density equivalent to red tide (1.5 to 5 × 1.6
(Cells / milliliter), the blue mussel efficiently ingests the bait particles in the seawater, and thus is effective in purifying the seawater. A field model was created based on the results for August 1997 to estimate what function the mussels attached to the rope in Dokai Bay were performing. First, 199
In August 2007, 5m length and width, 1m water depth (volume 25m
Assume that one rope is inserted into a box consisting of ³ ) volume of seawater. The nutrients loaded on Dokai Bay are summarized separately, but the nutrients loaded on this box have a DIN of 2.2 based on the volume ratio to the whole Dokai Bay.
4 g / day and DIP is 0.16 g / day. 8
The basic production rate per box per month is 24.9gC
/ Day. The feeding rate of mussels used the average value of the feeding rate per rope from July to August, and this value was calculated assuming that there was no local lack of food particles in the box. For the assimilation rate and excretion rate, values obtained from experiments were used.

The feeding rate of mussels per rope obtained from this experiment was equivalent to the basal production rate per 25 m ^{2 of} luminous layer at a water depth of 0 to 1 m, and was close to the Tobata Wharf Pier in Dokai Bay. Approximately 72% of the basic production in the basin was conducted at a water depth of 0 to 1 m. Therefore, if one rope is hung per 25 m ² of sea surface area in Dokai Bay, the growth of phytoplankton per unit area is 7
It was calculated to be down 2%. Although diatoms, the causative species of the red tide observed in this experiment, are said to have a higher growth rate than dinoflagellate and other phytoplankton known as harmful red tide plankton, It has a feeding rate that suppresses the growth of this species, suggesting that it can be removed in a short time except for red tide plankton that directly harms mussels. On the other hand, the daily DIN and DIP loads calculated from the volume ratio of the entire Dokai Bay to the box are 2.24 g and 0.16 g, respectively. The amount of assimilation per rope was calculated from the feeding rate and assimilation rate of mussels obtained from the experiment.
/ Day and P were 0.26 g / day. This is 1
70.1% of the amount of N loaded on the box per day and 1 for P
It was 63%, suggesting that the effectiveness of environmental restoration using mussels in Dokai Bay was suggested. In addition, it has been pointed out that the intestinal bacteria coexisting in the body are involved in faeces of mussels and their degradation is promoted, and the effect of suspended particles passing through mussels on the bottom of the seabed is reduced. It is thought to be done. Since bivalves actually produce dung, the dung is deposited on the seabed where the bivalves were, but this dung has the characteristic of being easily decomposed by bacteria. Since phosphorus is removed from seawater or freshwater, seawater or freshwater can be effectively purified.

The embodiment of the present invention has been described above.
The present invention is not limited to this embodiment, and any changes in conditions that do not depart from the gist are within the scope of the present invention. For example, in the present embodiment, an example has been described in which seawater is purified using bivalves of a type adapted to seawater. However, it is also possible to purify freshwater using bivalves adapted to freshwater. In addition, as an example of a string, a rope is hung in water.However, a large number of strings having dispersed yarns are combined to form a net or net, and the adhesion density of the bivalves attached to the net is reduced. You can also increase it.

[0023]

In the method for purifying seawater or freshwater according to the first to fifth aspects, a string having a large number of dispersing threads is hung in seawater or freshwater, so that the bivalve is kept in this state stably for a long period of time. Can be retained. Then, bivalves are selectively attached to the dispersion thread in a large amount, and are grown by feeding floating suspended organic matter, so that suspended matter in water containing phosphorus and nitrogen is eaten by the bivalves and imposes a burden on the environment. It is easily and efficiently removed without causing any damage to living organisms without causing damage to living organisms.In addition, a large amount of bivalves is easily collected and grown by pulling the string attached to the bivalves from the water. The resulting bivalves can be effectively used as feed, fertilizer, and the like.

In particular, in the method for purifying seawater or freshwater according to the second aspect, since the dispersion thread is formed in a ring shape, the bivalve foot thread attached to the dispersion thread does not easily fall off, and a string-like material is not formed. Can be effectively prevented from falling off of the bivalves held in the vessel. In the method for purifying seawater or freshwater according to claim 3, since the string-like material is made of biodegradable plastic, it is possible to easily attach the bivalve shell with an adhesive thread and the string-like material is long in the environment. It does not harm the ecosystem by remaining. In the method for purifying seawater or freshwater according to claim 4, the bivalves grown by feeding on suspended organic matter are pulled up at an appropriate time, and are used as they are or processed, and the bivalves are used as feed or fertilizer. In particular, when the string is formed of a biodegradable plastic, crushing treatment or the like can be applied without separating the string attached to the bivalve, and the waste can be efficiently treated without generating extra waste. In the method for purifying seawater or freshwater according to the fifth aspect, since the clams having an adhesive thread are mussels, the mussels having excellent reproductive properties and taste are particularly applied to efficiently purify and recover water bodies. And the effective use of the mussels.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a method for purifying seawater or freshwater according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the bivalve growth amount and the rope hanging period.

FIG. 3 is an explanatory view of a string-like object hanging in seawater.

FIGS. 4A and 4B are explanatory diagrams of a feeding experiment and a control experiment, respectively.

FIG. 5 is a graph showing the relationship between cell density in breeding water and elapsed time.

FIGS. 6A and 6B are graphs showing the relationship between elapsed time and nitrogen and phosphorus concentrations in breeding water, respectively.

[Explanation of symbols]

10: string-like material, 11: buoy, 12: mussels (bivalve with adhering toes), 20: rope, 21: dispersed yarn, 2
2: Upper hand rope, 23: Lower hand rope, 30: Water tank, 31: Erlenmeyer flask, 32: Funnel, 33: Purple mussel, 3
4: water tank, 35: air rate device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Machiko Yamada, Inventor 1-1, Jonai, Kokurakita-ku, Kitakyushu-shi, Fukuoka Prefecture (72) Naoko Ueda 1-2-1, Shinike, Tobata-ku, Kitakyushu, Fukuoka Kitakyushu Environmental Research Institute (56) References JP-A-9-66291 (JP, A) JP-A-9-70235 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 3/00-3/34 A01K 61/00-63/06

Claims (5)

(57) [Claims] 1. A string having a large number of dispersing threads is hung in seawater or fresh water, and a large number of bivalves having an adhesive thread are selectively adhered to the dispersing threads to feed floating suspended organic matter. A method for purifying seawater or freshwater, comprising growing, growing, and collecting on land. 2. The method for purifying seawater or freshwater according to claim 1, wherein the dispersion yarn has a ring shape. 3. The method for purifying seawater or freshwater according to claim 1, wherein the string is made of biodegradable plastic. 4. The method for purifying seawater or freshwater according to any one of claims 1 to 3, wherein the bivalve grown by feeding the suspended organic matter is raised at an appropriate time and left as it is. A method for purifying seawater or freshwater, wherein the method is processed and the bivalve is used as feed or fertilizer. 5. The method for purifying seawater or freshwater according to claim 1, wherein the bivalve with adhesive thread is a mussel.